1. Field of the Invention
The present invention relates to a method of manufacturing a magnetic detection apparatus capable of detecting the rotation angle of a gear-wheel shaped magnetic rotor for instance. and it also relates to a magnetic detection apparatus obtained by such a method of manufacture.
2. Description of the Related Art
There has hitherto been known a magnetic detection apparatus including a magnet and an IC chip, which is arranged in the neighborhood of this magnet and has a magnetoresistive element incorporated therein, for detecting the rotation of a toothed magnetic rotor from a change in the magnetic field which is applied to a magnetic sensing element and is changing in accordance with the rotation of the toothed magnetic rotor arranged in the proximity of the magnetic detection apparatus (for instance, see a first patent document: Japanese patent No. 3235553).
In such a known magnetic detection apparatus, when a positional displacement takes place between the magnet and the magnetoresistive element incorporated into the IC chip in the manufacturing processes of the apparatus, such a displacement results in a variation in a bias magnetic field. In this case, if the variation is large, there will arise a problem that the output of the magnetoresistive element does not cross a comparison level or threshold, resulting in a defective product which fails to generate any pulse output.